Vacuum-pump



i .2 Sheets-Sheet 1.

(No Model.)

W. E NIGKERSON. VACUUM PUMP.

No. 453,275. Patented June 2, 1 891.

a u v 6 j IT,

' No Model.) 2 Sheets-Sheet 2;

W. E. NICKERSON. VACUUM PUMP.

' No. 453,275. Patented June 2,1891.

I in connection with the accompanying drawin elevation.

UN TED STATES PATENT OFFICE.

XVILLIAM E. NICKERSON, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO THE BEACON VACUUM PUMP AND ELECTRICAL COMPANY, OF PORT- LAND, MAINE.

VACUUNl-PUMP.

SPECIFICATION forming part of Letters Patent No. 453,275, dated June 2, 1891. Application filed June 2, 1890. Serial No. 354,041. (No model.

To all whom it may concern.-

Be it known that I, WILLIAM E. NICKER- SON, of Cambridge, in the county of Middle{ sex and State of Massachusetts, have invented certain new and useful Improvements in Vacuum-Pumps, of which the following, taken ings, is a specification.

I Myinvention relates to that class of pumps usually called rotary pumps,. the objectbeing to so construct, combine, and arrange the pistons and their inclosing case that by the use of a sealing-liquid, which, in fact, is a component part of this pump, av good vacuum may be produced. This object I attain by the mechanism shown in the accompanying drawings, in which F gure 1 is a vertical section taken througl the center of the inclos'ing case, but showing the rotating pistons and a driving gear-wheel Fig. 2 is a horizontal section ofthe same. Fig. 3 is across vertical section of the case and showing the driving-gear and one of the pistons in side elevat on.

In the drawings, A B B represent the inclosing case. This case consists of the two side pieces 13 and B and the shell A, to which the side pieces B and B are bolted by screwbolts C C. The joints between the said pieces B B and the shell A are made tight by gaskets G G, arranged as shown in Figs. 2 and 3.

The two pistons D and D are made alike and without journals, they being arranged in connection with the side pieces B B, so that they may rotate on the cone-formed re-entering parts 0 c c c of the side pieces B B, the rotating pistons having cone-shaped recesses d d (1 cl on each side, as shown. The rotating pistons D and D are provided with teeth, the teeth of one piston interlocking with those of the other, so that the pistons must rotate together. One of the rotating pistons is turned by the pinion E,the shaft E of which passes through a stufling-box F into the pocket P, thence through the stuffing-box F, the inner end of the shaft E running in a socket E made for it in the case, as shown in Fig. 3.

The pipe L, Fig. 3, leads from the upper part of the pump to the lower and is adapted space below them. This pipe hasastop cook or valve L, ,by which the amount of oil that passes may be regulated. Usually enough oil will leak down or be carried down between the pistons to supply the oil required; but in case there should not be enough so supplied, .then'the pipe L may be used.

K, Figs. 1 and 3, is the outlet-pipe.

' This pump draws air from the article to be exhausted through the pipe N N, Fig. 3. The pipe N N, after leaving the lower part of the pump-chamber, turns upward to alevel higher than that of the oil in the pump-chamber, so that oil cannot run back into the article being exhausted, but will run out into the lower part of the pump chamber as soon as the pump starts.

This may be better understood by the following explanation: \Vhile the pump is in action no oil can run back, evenif the pipeNN did not turn upward; but when the pump is not in action the oil would by the impulse of gravity alone flow back from the pump into the pipe N N, and this flowing back would of course be much accelerated if a vacuum existed in the pipe NN' and its connections, as the pump would, when not working, admit of leakage through it, thus allowing the atmospheric pressure to drive the oil back through the pipe NN', and thence to the articles being exhausted. To guard against any possible backiiow of oil, the pipe N N may be carried to such aheight that the pressure of oil in it would exceed the pressure of the atmosphere. Then the lamps or other articles that have been exhausted. could be left in connection with the vacuum apparatus.

II II are vertical grooves made in the interior of the casings, and are intended to colleot any air that may have leaked between the end surface of the rotating piston and the side of the casings andadmit its return to the top.

The operation of the pump is as follows: There is an amount 01": oil in the chamber sufficient to seal all the parts, as shown in Fig 1. Now as the pistons rotate in the direction of the arrows the excess of oil in the lower between the teeth and the shell A-and as the ends of the teeth are nearly in contact with the shell A between the points h and h on both sides of the chamber their movement must carry the oil up with them, and as the oil is taken out of thelower part of the pump chamber a partial vacuum is formed there and air is drawn in through the pipe N. \Vhen the pump is working, the oil will stand about as indicated in the drawings, Fig. 1, there being some air and some oil in each tooth-space, as indicated, and there will be air in bubbles passing up through the oil in the upper part of the pump-chamber. Oil from the upper part of the chamber will be carried down between the rotating pistons, and thus keep the necessary supply in the lower part of the chamber.

I claim- 1. In a rotary pump, the combination of a piston-case adapted to hold a sealing-liquid, rotary pistons immersed in said sealing-liquid and so located in relation to each other that the sealing-liquid lies above and around the pistons and on the bottom of the case, so that the teeth of the pistons dip into it, while a clear space is left about the inlet-port, with an inlet-port connected by a pipe with the article to be exhausted, said inlet-port being above the level of the liquid in the bottom of the case and below the level of the centers of the pistons, and an outlet-port located above the pistons, substantially as and for the purpose set forth.

2. In a rotary pump, a case adapted to receive and retain a sealing-fluid, in combination with rotary pistons having comically-recessed ends adapted to fit accurately upon corresponding conical parts formed on the interior of the case, said conical parts being therebyadapted for bearings for the pistons to ro tate upon, no other bearings being required, substantially as and for the purpose set forth.

3. In a'rotary vacuum-pump, the combination of rotary pistons and their case adapted to hold a sealing-liquid above the level of the lowest dip of the members of the pistons, and also to hold a sealing-liquid above the level of the centers of the pistons, as described, with an inlet-port connected by a pipe w th the articles to be exhausted, said inlet being above the level of the liquid in the bottom of the case and below the level of the centers of the pistons, and the outlet-port and pipe L, adapted to convey the excess of the sealingliquid from above the pistons to beneath them, substantially as and for the purpose set forth.

l. In a rotary pump, the combination of a case adapted to contain rotary pistons and to hold above said pistons a sealing-liquid, and also to hold a sealing-liquid at the bottom of the case, as described, two rotary coactmg pistons, the bearings of which do not extend through the case, and inlet and outlet ports, as described, with a gear located within the said case, adapted to drive the said rotary pistons, and a shaft for said gear, adapted to transmit motion to it from without the case, substantially as and for the purpose set forth.

5. In a rotary pump, the combination of rotary pistons and their case, adapted to hold a sealing-liquid above the pistons and 111 the bottom of the case, as described, and an outlet-port located above said pistons, with an inlet-port located below the centers of the pistons and above the normal level of the sealing-liquid in the bottom of the case, said port having a pipe connecting the pump to the article to be exhausted and extended upward to a height which exceeds the level of the sealing-liquid in the case, so that when the pump is not in action the sealing-liquid in it will not run out of the case through the inlet-port, substantially as and for the purpose set forth.

6. In a rotary pump, the combination of the rotary pistons D D with the casings B B, having vertical grooves H H on their inner sides, substantially as and for the purpose set forth.

\VILLIAM E. NICKERSON.

Witnesses FRANK G. PARKER, WILLIAM EnsoN. 

